I want to know what i can do better with this gamehttps://www.youtube.com/watch?v=OvxsE4nor68
Sort out the animation on those arms out for a start. It looks like he’s still half in a T-pose with only his elbows moving.
You probably ought to remake the content yourself rather than porting from the original game. You’ll face enough issues with the IP copyright (even doing this for free), best not also have a bunch of ported content.
As a test project to get to grips with the tools it looks like you have spent quite a bit of time putting it together, but in reality it is just a port of the assets (unless I am mistaken)?
pbarnhardt is right in that you may face some issues with IP copyright (see this article) but for a bit of fun then why not.
how do i play the game with the engine
I would say improve graphic quality. It looks extremely low poly, with super sharp (maybe perfectly sharp) corners, like on the walls/structures. Those corners should be beveled/rounded.
Even though the character is extremely stylized, he would still fit into an environment that had a slightly more realistic style… Higher resolution textures, proper materials for models, etc.
U need to make the level a little bigger(atleast twice the map area) as well as a better walk/run animations . Make the textures and models relatively bigger by expoting the models from the scene and then create a bigger model by scaling it inside any good modelling tool .
About the animations use Mixamo
The models are all low poly because it’s all ported from the original game, which was made in 2002.
I agree with the previous posters. I know you’re probably a huge Harry Potter Fan but you would find greater satisfaction and respect by not porting from an older, and copyrighted game. Yeah, you could probably get away with the Hogwarts models but replace the textures with fresh, high-quality ones and make a new young wizard (or witch) in a new adventure, labeling it as a fan game instead of ripping off Chamber of Secrets.
Maximo is a great and free source to get you started on animation. Look into Adobe Fuse for the character help. I think they have younger models with clothing close enough to the Harry Potter world to make them work. Oh as for modeling itself try Blender. You can get some awesome tutorials at Blender Cookie
You could make one heck of a good Hogwarts story if you put your mind to it. Why limit yourself to Harry’s story (which is already complete) when you can create your own within the Hogwarts Universe. I can’t count the fan fiction I’ve seen on various sites when I decided to write my own fanfic, Harry Potter and the Five Fawks Wands. Of course, no one ever read it because I never completed it but I still wrote 7 chapters of it.